Very pretty bit of work, isn't it? I've been hoping to get a picture of some of the bees/wasps that have built a nest in the rock wall near my driveway. I haven't managed to get a good enough look at them to identify them well. They could be a variety of mining or digging bee or ground nesting wasp. They are on the fuzzy side, but have never been aggressive, are not terribly numerous, and similar in size to a honeybee. I confess to having been very lax in pruning or pulling a lot of the late flowering Aster weeds in the yard, because I continued to see bees visiting them until it turned cold. Given the continuing bad news for bees, I've been reluctant to deny the locals a food source, even if it doesn't look like much.

If you're interested in bees, here are two guides produced by the Forest Service that can provide you with more info.